By using this approach (called programmed electrical stimulation) Wellens not only unraveled mechanisms and localization of arrhythmias in the Wolff-Parkinson-White syndrome but also other types of supraventricular tachycardias.

In 1971, he reported on the use of programmed electrical stimulation of the heart in patients with atrial flutter, AV nodal tachycardia, and accessory atrioventricular connections.

In 1972, he showed that the arrhythmia of patients with ventricular tachycardia could also reproducibly be initiated and terminated by timed premature stimuli.

[2] Wellens left Amsterdam in 1977 to become Professor and Chairman of the Department of Cardiology at the Academic Hospital of the new Maastricht University.

Wellens was a student Professor Dirk Durrer in Amsterdam and participated in the early development of programmed electrical stimulation of the heart in patients with Wolff–Parkinson–White syndrome.

[5] Articles in memoriam of Hein Wellens were published by European Society of Cardiology, authored by past president of European Heart Rhythm Association Karl-Heinz Kuck[6] and by Latin American Heart Rhythm Society, authored by Josep Brugada and Jacob Atié.